An international consortium of scientists has completed a joint survey of the cosmos analysing several million galaxies and quasars to create the largest 3D map of the Universe.

The six-year-long survey, known as the Extended Baryon Oscillation Spectroscopic Survey” (eBOSS), was initiated and partly led by Jean-Paul Kneib, an astrophysicist from Lausanne’s Federal Institute of Technology (EPFL).

The 3D map is the fruit of a 20-year collaboration with several hundred scientists from 30 different institutions around the world. They came together as part of the “Sloan Digital Sky SurveyExternal link” (SDSS), which uses data collected from an optical telescope located in New Mexico, in the United States.

The map was releasedExternal link on July 20 as 20 scientific publications.

“In 2012, I launched the eBOSS project with the idea of producing the most complete 3D map of the Universe throughout the lifetime of the Universe, implementing for the first time celestial objects that indicate the distribution of matter in the distant Universe, galaxies that actively form stars and quasars,” said Jean-Paul Kneib in a statement. “It is a great pleasure to see the culmination of this work today.”

EPFL said the survey builds upon existing data from 1998 and fills gaps in cosmological history in order to improve understanding of the mechanisms underlying the expansion of the Universe. Scientists say the Big Bang that gave rise to the Universe occurred 13.8 billion years ago.

To complete the survey the researchers measured recurring patterns in the distribution of galaxies to identify several key cosmological parameters, including the density of hypothetical dark matter and energy in the Universe.

The EPFL statement said teams studied galactic tracers that reveal the mass distribution in the Universe. For the part of the map relating to six billion years ago, they observed the oldest and reddest galaxies. For more distant eras, they concentrated on the youngest galaxies, the blue ones. To go back further to eleven billion years, they examined quasars, galaxies whose super-massive black hole is extremely luminous.

“We know both the ancient history of the Universe and its recent expansion history fairly well, but there’s a troublesome gap in the middle 11 billion years,” said cosmologist Kyle Dawson of the University of Utah, who leads the team announcing the results. “Thanks to five years of continuous observations, we have worked to fill in that gap, and we are using that information to provide some of the most substantial advances in cosmology in the last decade.”